public void SetArcSegmentItem(ArcSegmentItem item, double radius, double sin, double cos, Rect sectorRect)
 {
     item.Size            = new Size(radius, radius);
     item.StartPoint      = new Point(sectorRect.Width / 2 - sin * radius, sectorRect.Height - cos * radius);
     item.EndPoint        = new Point(sectorRect.Width - sin * radius, sectorRect.Height - cos * radius);
     item.StrokeThickness = 20.0;
 }
        private void ArrangeChildren(Size finalSize)
        {
            //开始考虑加入ItemsPanel, 这里transform的中心点还是不能用整个圆心做为中心点,不然的话不是以第一个item为开始
            if (Children.Count == 0)
            {
                return;
            }

            var count = Children.Count;
            //Get the radius of the available size.
            double radius = Math.Min(finalSize.Width, finalSize.Height) * 0.5;
            //child angle
            double childAngle = 360.0 / (Math.Max((double)count, 2));
            //sin
            var sin = Sin(childAngle / 2);
            //cos
            var cos = Cos(childAngle / 2);
            //SampleRect
            var SampleRect = new Rect {
                Width = 2 * sin * radius, Height = radius
            };

            SampleRect.X = radius - SampleRect.Width / 2.0;
            //给当前Item的Arcsegment进行赋值
            var baseitem = new ArcSegmentItem();

            SetArcSegmentItem(baseitem, radius, sin, cos, SampleRect);


            //loop
            for (int i = 0; i < Children.Count; i++)
            {
                RadialMenuItem  element   = (RadialMenuItem)Children[i];
                RotateTransform transform = new RotateTransform();
                transform.CenterX = SampleRect.Width / 2.0;
                transform.CenterY = SampleRect.Height;



                //transform.CenterX = radius;
                //transform.CenterY = radius;
                var angle = childAngle * i;
                transform.Angle = angle;
                element.ArcSegments.BasePanel = baseitem;
                element.ContentAngle          = -angle;
                element.RenderTransform       = transform;
                element.Arrange(SampleRect);
            }
        }